/Engine/Source/Runtime/Engine/Classes/GameFramework/Actor.h
Calculates the actor space bounding box of all components in this Actor. This is slower thanGetComponentsBoundingBox(), because the local bounds of the components are not cached  they are recalculated every time this function is called.
virtual FBox CalculateComponentsBoundingBoxInLocalSpace ( bool bNonColliding, bool bIncludeFromChildActors ) const